Method of making blower wheels



. Jan. 27, 1959 w s METHOD OF MAKING BLOWER WHEELS Filed 0013. 14. 1957 s M 9R L A E 1 5W s. ,8 W m; e r E m x j s w H M w w E E P M a 0 A A ll 1..

METHOD OF MAKING BLOWER WHEELS John H. Wessel, Los Angeles, Calif., assignor to Utility Appliance Corp., Los Angeles, Calih, a corporation ofCalifornia Application October 14, 1957, Serial No. 689,856

1 Claim. (Cl. 219-150) The present invention relates in general to a method of making fans and, more particularly, to a method of securing together in a rigid and permanent manner an assembly of fan components comprising a plurality of circumferentially spaced blades or vanes provided with lugs or tabs which project through openings in one or more mounting members. In the construction hereinafter described in detail for illustrative purposes, the invention is considered as applied to a blower wheel which includes an assembly comprising a plurality of circumferentially spaced, longitudinal vanes each having at each end thereof at least one tab which projects through an opening in a mounting member at the corresponding end of the assembly, there preferably being two tabs at each end of each vane to provide more rigid connections between the vanes and the mounting members therefor.

In permanently securing together an assembly of blower wheel components of the foregoing character, it is necessary to deform the projecting portions of the tabs so as to lock the vanes and the mounting members together. In Patent No. 1,637,652, granted August 2, 1927, to William H. C. Ness, the projecting portions of the tabs are bent over, i. e., clinched, against the mounting members to permanently interconnect the vanes and the mounting members. This procedure suifers from the disadvantage that permanently rigid conections between the vanes and the mounting members, i. e., connections which will not loosen with the passage of time under vibration and the like, are difficult or impossible to obtain. Patent No. 2,392,113, granted January 1, 1946, to Axel F. L. Anderson, discloses a process wherein the projecting portions of the tabs are cold riveted against the mounting members. With this procedure, it is also difficult, if not impossible, to obtain connections between the vanes and the mounting members rigid enough to withstand prolonged usage without. loosening of the vanes.

' A primary object of the invention is to provide a method of deforming the projecting portions of the tabs in sucha manner as to provide permanently rigid connections between the vanes and the mounting members.

More particularly, a basic object of the invention is to rivet the projecting portions of the tabs against the mounting members while the tabs are heated, such hot riveting of the tabs producing a very strong and permanently rigid blower wheel since shrinkage of the hot riveted tabs as they cool pulls the mounting members very tightly against the ends of the blades. Also, the holes in the mounting members are completely filled by the hot riveted tabs to eliminate lateral play of the vanes. Thus, strong and permanently rigid connections, impossible of achievement with clinched or cold riveted tabs, are attained, which is an important feature of the invention.

Another and key object of the invention is to provide a method of hot riveting the projecting portions of the tabs on the vanes over the mounting members at the ends of the vanes which involves resistance heating of the tabs,

atent O 2,871,340 Patented Jan. 27, 1959 i. e., which involves heating the tabs by passing electric current therethrough.

More specifically, an important object of the invention is to provide a method which includes the steps of contacting the projecting portion of each tab with an electrode, passing electric current through the electrode and the tab in contact therewith to heat the tab to a temperature at which it may be riveted readily, and then relatively moving the electrode and the assembly of vanes and mounting members toward each other while the electrode is in contact with the heated tab so as to rivet the projecting portion of the heated tab against the adjacent mounting member, subsequent shrinkage of the hot riveted tab as it cools resulting in pulling the adjacent mounting member very tightly against the corresponding blade end. To some extent at least, the hot riveting operation also results in welding of the tabs to the mounting members, which is an important feature.

Another object of the invention is to provide a method of hot riveting two projecting tab portions simultaneously by means of two electrodes in contact with two tabs on the same vane, the electric current utilized for resistance heating of the tabs passing from one electrode to the other through the tabs in contact with the electrodes and through at least a portion of the corresponding vane.

Still another object is to provide a method wherein two tabs at one end of a vane are resistance heated and hot riveted simultaneously by two electrodes at one end of the assembly and respectively engaging such tabs.

A further object is to provide a method whereby tabs at opposite ends of a vane are resistance heated and hot riveted simultaneously by two electrodes respectively engaging such tabs.

Yet another object is to provide a method wherein electrodes at opposite ends of the assembly are utilized to heat and rivet four or more tabs on a single vane simultaneously.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in this art in the light of the present disclosure, may be attained with the exemplary embodiments of the invention described in detail hereinafter and illustrated in the accompanying drawing, wherein:

Fig. l is a perspective view of the blower wheel made in accordance with the method of the present invention;

Fig. 2 is a fragmentary perspective view on an enlarged scale illustrating one embodiment of the method of the invention; and

Fig. 3 is a fragmentary perspective view illustrating another embodiment of the method of the invention.

In the drawing, the numeral it designates a blower wheel, which, for purposes of illustration only, is shown as including two axially or longitudinally aligned sections 12, it being understood that the invention may be applied to blower wheels having any desired number of sections. Each blower-wheel section 12 includes two axially or longitudinally spaced mounting members i4 and i6 and a plurality of circumterentially spaced, longitudinal blades or vanes 18 extending between and connected at their ends to such mounting members.

in the particular construction illustrated, the mounting members 14 are located at the respective ends of the blower wheel 10 and are simple rings, the mounting memberslo'being located intermediate the ends of the The vanes 18 of each blower-wheel section 12 are provided with longitudinally extending lugs or tabs at their ends, there preferably being at least two such tabs at each end of each vane to provide more rigid connections between the vanes and the mounting members 14 and 16. The tabs 20 at the ends of each vane 18 project longitudinally through openings 22 in the corresponding mounting members 14- and 16, as best shown in Figs. 2 and 3 of the drawing.

Considering now the embodiment of the invention illustrated in Fig. 2 of the drawing, the mounting members 14 and 16 and the vanes 18 of each blower-wheel section 12 are first assembled with the tabs 20 on the vanes projecting through the openings 22 therefor in the mounting members, the mounting members and the vanes being temporarily held in assembled relation in any suitable manner. Next, electrodes 24 are brought into contact with the ends of the tabs 20 at one end of each vane 18 and an electric current is passed from one electrode to the other by way of the tabs in contact with the electrodes and a portion of the corresponding vane, the current path being indicated by the arrowed line 26 in Fig. 2 of the drawing, which figure shows the electrodes in position to engage two of the tabs adjacent the mounting member 14. Contact between the electrodes 24 and the ends of the tabs 20 at one end of each vane 18 may be established by movement of the electrodes toward the tab ends, or vice versa.

Passage of current through the tabs 20 in contact With the electrodes 24 along the current path 26 results in resistance heating of these tabs and, when the tabs attain a sufiiciently high temperature, the electrode pressures applied thereto result in riveting of the projecting portions of the tabs against the mounting member 14, as indicated by the numerals 28. It will be understood that the tabs 26 on each vane 18 adjacent the mounting member 16 may be riveted against this mounting member by means of the electrodes 24 or another pair of such electrodes, in a similar manner.

In the embodiment of the invention illustrated in Fig. 3 of the drawing, two electrodes 30, each large enough to engage both of the tabs 20 at one end of each vane 18, are utilized. With this construction, electric current flows through all of the tabs 20 on a particular vane 18 along parallel current paths 32, all of the tabs on a particular vane thus being subjected to resistance heating simultaneously. When heated sufiiciently, the tabs 20 at both ends of each vane 18 are then riveted simultaneously as the result of the electrode pressures applied thereto, tabs riveted against the mounting member 14 being designated by the numeral 34 in Fig. 3 of the drawing. Thus, whereas two simultaneous or sequential resistance heating and riveting operations are required with the embodiment of Fig. 2 to rivet the tabs 20 at both ends of a particular vane 18, this is accomplished in a single resistance heating and riveting operation in the embodiment of Fig. 3.

It will be understood that, if desired, the embodiment illustrated in Fig. 3 of the drawing may be utilized to resistance heat and rivet only two tabs 20, one on each end of a particular vane 18, at a time by making the electrodes 31) of a size to engage only one tab at a time, instead of two as shown.

In order to rivet the tabs 20 against the mounting members 14 and 16 after resistance heating thereof by the electrodes 24 and 30, it will be apparent that relative movement of the electrodes and the mounting members toward each other must occur to sustain the electrode pressures on the heated tabs necessary to produce riveting. In the embodiment of Fig. 2, this may be accomplished 4 either by moving the electrodes 24 toward the assembly of mounting members 14 and 16 and vanes 18, or vice versa. In the embodiment of Fig. 3, this may be accomplished by moving the electrodes 30 toward each other. It will be understood that the temperature to which the tabs 20 must be heated to permit riveting thereof by the electrodes 24 and 3t depends on the tab material and on the electrode pressures utilized. In other words, the tab temperature may be relatively low if the temperature at which the tab material may be riveted satisfactorily is low, and vice versa. Similarly, the tab temperature may be reduced by increasing the electrode pressure utilized for riveting, and must be increased if the electrode riveting pressure is reduced.

The method of the present invention produces very strong and rigid blower-wheel sections 12. The primary reason for this is that, as the riveted tabs 28 and 34 cool, they contract or shrink an amount proportional to the thermal coefiicient of expansion of the vane material, with the result that the mounting members 14 and 16 are pulled solidly against the ends of the vanes 18. Also, hot riveting of the tabs 20 in accordance with the invention results in riveting the tabs against the mounting members 14 and 16 very tightly even before cooling of the tabs begins and results in complete filling of the holes in the mounting members and in Welding of the tabs to the mounting members to some extent at least. Thus, the present invention provides a sturdy blower wheel the vanes of which will not loosen in use, which is an important feature of the invention.

Another feature of the invention is that hot riveting of the projecting portions of the tabs 20 requires the application of electrode pressures much smaller than the clinching forces required with the procedure of the aforementioned Ness patent, or the cold riveting forces of the aforementioned Anderson patent. Consequently, there is very much less likelihood of distortion of the Various components during the process of securing the mounting members 14 and 16 and the vanes 18 of each blowerwheel section 12 together, which is another important feature.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood thatvarious changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claim which follows.

I claim as my invention:

A method of securing together an assembly of fan components comprising a plurality of circumferentially spaced, longitudinal vanes having at their ends tabs which project through openings in mounting members at the ends of said assembly, each of said vanes having two of said tabs at each end thereof, said method including the steps of: contacting the projecting portions of said tabs at each end of each of said vanes with electrodes; passing electric current from one of said electrodes to the other through the tabs contacted by said electrodes, and through an end portion of the correspending vane, so as to heat such tabs; and relatively moving said electrodes and said assembly longitudinally toward each other while said electrodes are in contact with said heated tabs so as to rivet said projecting portions of said heated tabs.

References Cited in the file of this patent UNITED STATES PATENTS 1,554,385 Still Sept. 22, 1925 

